In particular, he argues that if Greece leaves the euro, the effects on the UK economy could be significant, not just in the short term, but in the long term too.

The concern is that you end up with an outcome in the eurozone that creates the same sort of structural difficulties in the financial system and in the economy that we saw in the past recession, and that that has consequences both for hitting economic activity in the economy, but also its underlying potential. And it’s the latter which has particular difficulties for the fiscal position, because it means not just that the economy weakens and then strengthens again – ie, it goes into a hole and comes out – but that you go down and you never quite get back up to where you started. And that has more lingering, long-term consequences for the public finances.

The interview looked not just at the effects of the current crisis in the eurozone on the eurozone, British and world economies, but also at a number of other issues, including: the reliability of forecasts and those of the OBR in particular; relations between the OBR and the Treasury; allowing the OBR to cost opposition policies; the economic effect of cutting the 50p top rate of income tax; the sustainability of public-sector pensions; and tax increases or spending cuts in the long term.

In Part 3 we look at attempts by the G8 countries to find a solution to the mounting crisis.

Under its terms of reference the new Office for Budget Responsibility is required to provide updated forecasts for the economy and the public finances at the time of each Budget in order take into account the impact of those measures contained in the Budget. Here we consider those economic forecasts contained in the June 2010 OBR Budget Forecast relating to economic growth. In particular, we consider the OBR’s interpretation of how growth is likely to be affected by the policy measures unveiled by George Osborne in his first Budget as Chancellor of Exchequer on 22 June.

The OBR forecasts that the UK economy will grow by 1.2% in 2010 and by a further 2.3% in 2011. These estimates are lower than those published by the OBR in its Pre-Budget Forecast published on 14 June. The Pre-Budget Forecasts predicted growth of 1.3% in 2010 and 2.6% in 2011. The downward revisions reflect the OBR’s assertion that the Budget’s measures to meet the Government’s fiscal mandate and, hence the resultant fiscal consolidation package, will weaken aggregate demand.

In terms of the components of aggregate demand, the fiscal consolidation will mean restraints on government spending (G) and, if the OBR is right, lower growth in household consumption (C). Lower consumption growth is expected as a result of reduced growth in household incomes and the rise in the standard rate of Value Added Tax next January from 17½% to 20%.

The OBR now forecasts that real household consumption will grow by just 0.2% in 2010, following last year’s contraction of 3.2%, and by 1.3% in 2011. General government final consumption – the Government’s expenditure on current goods and services – is forecast to grow in real terms by 1.7% this year before falling by 1.1% next year. The forecasts for general government capital spending are for a real fall of 4.9% this year, following last year’s rise of 15.7%, followed by a sizeable 19% decline in 2011.

A more positive note emerging from the OBR forecasts relates to capital expenditure by businesses. The measures to reform corporation tax, which include a reduction in the main rate of corporation tax from 28 per cent to 24 per cent over four years beginning with a one per cent reduction from April 2011, are predicted to have a favourable effect on investment. Business investment is forecast to rise in real terms by 1.4% this year, following last year’s fall of 19.3%, and to rise again in 2011 by 8.1%.

The projections for growth from 2013 are now stronger than in the OBR’s Pre-Budget Forecast with the economy portrayed as adjusting more quickly at this point towards its potential output. Potential output is the level of output level when the economy’s resources are operating at ‘normal capacity utilisation’. But, in 2015, which is at the end of the OBR’s five year forecast period, the UK economy is still forecast to be experiencing a negative output gap. In other words, actual output will still be less than potential output.

To help paint a picture of how the economy’s output will adjust towards its potential level consider the OBR estimates for the output gap. The OBR estimates that in financial year 2009-10 the economy’s output was 4.1% below its potential. This negative output gap is now expected to be reduced to 3.7% of potential output in 2010-11, to 2.8% in 2012-13 and to 0.9% of potential output in 2015-16.

What are the component expenditures of aggregate demand? Which of these do you think is the largest in value terms?

The OBR is forecasting the household sector’s disposable income to grow in real terms this year by 0.2% and by 1.2% next year. Why then is the OBR identifying weaker consumer demand as a result of the Budget measures as a major reason for revising down its predictions for economic growth?

The OBR argues that the fiscal consolidation measures will have a ‘direct effect’ on household incomes and so on spending, but that this will be ‘partially offset by a decline in saving’. Why might the OBR be arguing that a fiscal consolidation will lead to a decline in saving? Evaluate the OBR’s arguments.

What do you understand by the concept of an output gap? What does a negative output gap signify?

To see the sorts of problems that forecasters commonly face, try identifying reasons why the output gap could be eliminated more quickly or less quickly as a result of the Budget measures.

As one of his first acts, the new UK Coalition government’s Chancellor, George Osborne, set up an independent Office for Budget Responsibility (OBR) (see Nipping it in the Budd: Enhancing fiscal credibility?. The role of the OBR is to provide forecasts of the economy and the data on which to base fiscal policy.

On 14 June, the OBR produced its first forecast in time for the Budget scheduled for 22 June. It has some bad news and some good news. First the bad news: it forecasts that growth for 2011 will be 2.6% – down from the 3–3.5% forecast by Labour in its last Budget in March. But now the good: it forecasts that the public-sector deficit in 2010/11 will be 10.5% of GDP – down from the 11.1% forecast by Labour; and that public-sector debt will be 62.2%, not the 63.6% forecast by Labour. These forecasts are before any policy changes announced in the Budget on 22 June.

Meanwhile, the accountants BDO have published a survey of business confidence. This shows the largest drop since the survey began. Talk by the government of cuts and worries that this will impact directly on the private sector have caused many businesses to cut investment plans. The worries are compounded by fears of a decline in export demand as countries abroad also make cuts.

So what does the future hold? Should we put any faith in forecasts? And should we be more worried about a double-dip recession or by failure to make sufficient inroads to deficits to calm markets?

How reliable is the OBR’s forecast likely to be? What factors could cause the forecast for economic growth to be (a) an overestimate; (b) an underestimate?

What is likely to happen to aggregate demand over the coming months? Explain.

What is meant by the ‘structural deficit’. Why might the structural deficit fall as the economy recovers? Would you explain this in terms of a shift or a movement along the short-term aggregate supply curve?

Which is the greatest threat over the long term: inflation or deflation?

Do you agree that the debate about cutting the deficit is merely a question of timing, not of the amount to cut?

Why may policies of fiscal tightening, if carried out generally around the world, involve the fallacy of composition?

Is there any common ground between the fiscal ‘hawks’ and fiscal ‘doves’ (see the last Guardian article above)?